<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="x-dns-prefetch-control" content="on" />
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <script>


  </script>
</head>

<body>


  <button id="btn">load</button>


  <script>

    document.getElementById('btn').addEventListener('click', function () {
      const link = document.createElement('link');
      link.rel = 'stylesheet';
      // link.rel = 'preload';
      // link.as = 'style';
      link.href = './css/common.css';
      document.head.appendChild(link);
    })

  </script>


</body>

</html>